Means and method of perforating well casings



Feb. 4, 1936.- w. T. WELLS MEANS AND METHOD OF PERFORATING WELL CASINGS filed July 7, 1954 /N VENTO/e t fh v vE 4 2.

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Iman Patented Feb. 4, 1936 UNITED STATES PATENT OFFICE Walter T. Wells, Glendale, Calif., assignor to The Technicralt Engineering Corporation, Los Angeles, Calif., a corporation of California Application July 7, 1934, Serial No. 734,171

19 Claims. (Cl. 81-188) My invention relatesl to means and method of perforating well casing, and the objects of my invention are:

First, to provide a means of perforating well casing which involves the firing of projectiles through the well casing;

Second, to provide a means of this class which is particularly designed for ring projectiles while submerged to great depths in water, oilm well mud orv the like, there being incorporated an arrangement whereby the uid through which the projectile must pass is readily displaced;

Third, to provide a method of perforating well casing which involves perforating the casing by 1;, gun-lire while submerged in a non-compressible fluid, but providing a compressible region in proximity to the location being perforated whereby the effect of the gun fire on the inertia of the non-compressible iiuid head is minimized;

Fourth, to provide a means and method of this class which is particularly applicable to the per- `forating of a. plurality of concentric casings as well as what cement there may be between and around the casings; and

Fifth, to provide on the whole a novel means of perforating well casing which is simple of construction, and positive in its operation.

With the above and other objects in view as may appear hereinafter attention is directed to the accompanying drawing, wherein similar characters of reference refer to similar parts and portions.

In the drawing; Figure 1 is an elevational view of a gun type perforator embodying my invention and showing the same within a well bore wherein several casings are provided; and, Figure 2 is an enlarged fragmentary sectional view ofthe perforator taken through 2-2 of Figure 1.

The gun type perforator which is incorporated with my improved means consists generally of an elongated, cylindrical body member I in which are formed a plurality of staggered, laterally directed sockets la. These receive gun casings 2 which are preferably removable from the body member.

Each gun casing is provided with a recess 2a which is enlarged at its outer portion and receives a short gun barrel 3. 'Ihe remaining portion of the recess 2a forms chamber 2b which receives an explosive containing cartridge 4. The gun barrel forms a sealed connection with the casing and its bore is sealed from the chamber 2b by a partition 5. The partition 5 is relatively strong to cause an initial pressure to be built up in the chamber 2b before the explosive 'ruptures the partition and discharges through the gun bore. A projectile 'l is tted in the gun bore.

The cartridge 4 is provided with an element not shown adapted to be heated to incandescence by suitable electrical means including a conductor extending through a cable 8 which supportsl the body I. Also a selector device, not shown, is incorporated in the electrical means and mounted within the body number I, for the purpose of iiring the gun units one at a time or in prearranged groups.

I do not claim the above described structure per se but in combination with the apparatus hereinafter set forth; inasmuch as said structure is the invention of one Wilfred G. Lane and embodied in a co-pending application Serial Number 642,410, filed November 12, 1932.

It is desirable and often mandatory that the gun type perforator be discharged while submerged -to relatively great depths in water, oil- 20 well mud or the like. The water or oil-well mud is incompressible so that in order for a projectile to leave the perforator the whole column of liquid must be displaced upwardly suiiiciently to compensate for the volume of the projectile. When 2f such liquid column is long the inertia is so great that much of the energy is dissipated in moving the column. v Y

I overcome this diiculty by providing a compressible medium in proximity to the gun unit, 30 that is within a few feet of the gun unit. In the form shown, an air receiver 9 is secured to the lower end of the body member i, preferably by a screw connection HI. Said receiver is in the form of an elongated hollow cylinder having a 35 closed upper end 9a, and a blunt pointed lower end 9b with a centered opening 9c therein.

The air receiver is suiciently long that when the perforator is submerged to its working depth and water or ol well mud has compressed air 40 into the upper end of the receiver, the`volume of such entrapped air will be greater than the volume of liquid to be displaced. Suicient excess volume of air should be provided so that the necessary reduction in its volume will not cause a 45 material change in its pressure thereby reducing to a minimum the energy dissipated in moving the liquid. In Figure 2, the character X designates approximately the liquid to be displaced and Y in the air receiver designates the 50 corresponding rise in liquid and the displacement occurs in the direction of the arrows.

I This construction forms a surge chamber for displaced fluid that acts as a shock absorber for the pressure resulting from the discharge of the 55 gun unit and minimizes the retarding action that the inertia of the incompressible uid head would have on the velocity of the projectile.

The gun perforator is designed to re one gun unit at a time and a sumcient interval occurs between iring that the liquid returns to its static pressure and'theexcess liquid flows out of the airreceiver.

Under some conditions the casing is sufficiently yieldable to permit operation of the perforator. but when it is necessary to perforate several casings with cement .betweenA or a single casing with an excessive amount of cement therearound, the casing is practically rigid and my device becomes particularly effective. It should be understood, however, that under all conditions regardless of a slight yieldability ofthe casing, my device increases the efficiency of the perforator.

My method of perforating well casing consists in lowering a gun type perforator into a well casing while maintaining thefcasing full of an incompressible liquid such as water or oil well mud in order to prevent blow outs or other diifculties caused by subterranean pressures, then firing the perforator while so submerged, and cushioning the pressure orabsorbing the shock of said firing in proximity to the perforator. And further, where there are several gun units carried by a single body member, each or a predetermined group of gun units is fired selectively with sufficient pause to enable the liquid to regain its static condition.

I claim:

1. 'Ihe combination with a gun type perforator adapted to be submerged in an incompressible medium; of an air receiver secured to the perforator, said receiver being closed at its upper end and open at its lower portion whereby said medium compresses air therein when submerged. Y

medium; of an air receiver secured to the perforator, said receiver being closed at its upper end and open at its lower `portion whereby said medium compresses air therein when submerged, the air receiver having sucient capacity that the resulting volume of air therein when the perforator is submerged to its working depth yis greater than the volume of said medium to be displaced upon discharge of said perforator.

3. In a well casing perforator. a submergible gun unit arranged to discharge a projectile laterally through a well casing, flringmeans therefor, and a yieldable means disposed in proximity to the gun unit and responsive to variation in the pressure of an incompressible medium in which the gun unit is submerged, to permit displacement of said medium upon the discharging of a projectile from said gun unit.

4. In a Well casing perforator, a submergible gun unit arranged to discharge a projectile laterally through a well casing, firing means therefor, and al compressible fluid receiver disposed in proximity to the gun unit, said receiver also arranged to receive an incompressible iiuid into which the gun unit is submerged, to permit displacement of said medium upon the discharging of a projectile from said gun unit.

mit displacement of an incompressible liquid when the gun units merged therein.

6. The combination with a device for perforating a well casing in place within a well hole which' device comprises a body, an l'explosive charge within the body, said body having means for -directing'the force of the` explosive'against a well casing, andv being of sufilcientstrength'to resist the destructive force of said charge and means for detonating the charge when lowered down a liquid lled weil hole; of a compressible means in proximity to said body to facilitate displacement of said liquid.

7. In a device for perforating a well casing in place in a well hole, the combination of an explosive charg'e, a body holding the explosive charge, said body being suiiiciently strong to resist the force of the explosive charge, lateral ways for directing the force of the explosive to,- Wards the well casing, slugs normally closing the ways, means for detonating the explosive while in place within a liquid filled well hole, and

L,are discharged while suba compressible instrumentality in proximity to said body to facilitate displacement of said liquid upon discharge of said slugs.

8. The combination with an explosive charge, means for submergingv the charge in an incompressible medium, amd an instrumentality for ring the charge while so submerged; of a variable volume uid cushion means disposed in proximity to the explosive charge and arranged to accommodate a quantity of said medium displaced upon ring of said'explosive charge.

9. The combination with an explosive charge, means for submerging the charge in an incompressible medium, and an instrumentality for ring the charge while so submerged; of a compressible uid; and a container therefor adapted to be submerged with the explosive charge in proximity thereto; said container normally communicating with the incompressible medium4 whereby upon ring the explosive charge a quantity of said 'medium is displaced into a portion of the spacev occupied by the compressible uid.

10. A gun type perforator adapted to be positioned in a well casing containing an incompressible medium, means for -discharging the gun when submerged, and a shock absorber for the discharge pressuregvon the incompressible medium disposed in proximity to the perforator.

11. The combination with a gun type perforator adapted to be submerged in an incompressible fluid in a well casing, of a shock absorber for the pressure on the incompressible iiuid resulting from the discharge of the gun when submerged positioned in proximity to the perforator.

12. The combination with a gun type perforator adapted to be submerged and fired in an incompressible fluid in a Well casing, of a surge chamber for the vincompressible uid carried thereby.

13. A gun type perforator adapted` to be submerged in .a well casing containing an incompressible uid and fired therein, and means for cushioning the fluid displacement resulting from the ring in proximity to the perforator.

14. In a well casing perforator, a gun unit submerged in a well casing containing an incompressible'fluid, a projectile red therefrom and passing through the fluid and casing, and means for cushioning the effect of the uid displaced in the path of the projectile arranged in proximity to the perforator.

15. A gun type perforator adapted to be submerged in an incompressible duid, means for firing the gun when submerged, and said periorstor containing a coniined compressible iluid in communicntion with the incompressible fluid for taking up the surge resulting from the discharge of the gun.

16. A method of periorating a. well casing ln place in a well hole and containing an incompressible medium which comprises submerging a gun type periorator therein, dischm'sin a projectile therefrom by gun nre through the medium and casing, and absorbing the medium displaced by the passage of the projectile therethrough in proximity to the perlorator.

17. A method oi periorating a well casing containing an incompressible iluid which comprises submersing s gun type perforator containing a. compressible fluid therein, the gun charge o! the gun through compression o! the iiuid in the periorstor.

18. A method ot periornting s well casing in place in a. well hole and containing an incomprsible iiuid which comprises submerging s gun type periorator therein, discharging the gun while submerged to periorste the casing, and cushioning the pressure resulting from thedischarge of the gun in proximity to the periorstor.

19. A method oi periorating a well casing containing an incompressible iiuid which comprises submersins a. plurality of periorator guns there in, successively firing said guns to periorate the casing, cushioning the pressure resulting from each gun discharge on the incompressible iluid in proximity to the gun, and allowing a sunicient time interval to elapse after each iiring for the while submerged to peri'orate the casing, and. incompressible iiuid to become static.

cushioning the pressure resulting from the dis- WALTER T. WELLS. 

